In wireless communication systems, to facilitate efficient closed loop downlink multiple-input and/or multiple-output (MIMO) operation, accurate pre-coding matrix index (PMI) and channel quality indicator (CQI) estimation is involved at the mobile station (MS) or subscriber station (SS). In order to facilitate MIMO operation, a midamble may be utilized in the downlink subframe. The MIMO midamble may be utilized for PMI selection and CQI calculation in a closed loop MIMO system, and to calculate CQI in an open loop MIMO system.
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